Review of High-PPI Micro-LED Display Drivers with Current-Mode PWM and Compact Pixel Circuits for Near-Eye Applications

T.-H. Lo (National Tsing Hua Univ., Taiwan), C.-W. Lu (NTHU, Taiwan)

This paper reviews recent advances in high-pixel-density micro-LED display drivers for near-eye applications. With the increasing demand for augmented and virtual reality systems, micro-LED displays have emerged as a promising solution due to their high brightness, fast response time, and excellent energy efficiency. However, achieving high resolution and high grayscale accuracy simultaneously presents significant challenges in pixel circuit design and data-line driving capability. This work reviews two micro-LED display driver designs fabricated in 0.18-μm CMOS technology, featuring current-mode pulse-width modulation (PWM) and compact pixel circuits. The first design employs a 2-transistor (2T) pixel circuit with a precharge scheme to enhance driving speed for a 1280 × 720 display. The second design introduces a 1.15-transistor pixel circuit using a three-stage pass-transistor structure to achieve ultra-high pixel density of 7700 PPI. Both designs utilize down-counter-based PWM generation for accurate grayscale control. Through comparative analysis, this paper highlights key design trade-offs among pixel circuit complexity, driving speed, power consumption, and pixel density. These techniques provide valuable insights for future micro-LED display driver design targeting next-generation near-eye displays.